Problem: William is 4 times as old as Ashley and is also 27 years older than Ashley. How old is William?
Solution: We can use the given information to write down two equations that describe the ages of William and Ashley. Let William's current age be $w$ and Ashley's current age be $a$ $w = 4a$ $w = a + 27$ Now we have two independent equations, and we can solve for our two unknowns. One way to solve for $w$ is to solve the second equation for $a$ and substitute that value into the first equation. Solving our second equation for $a$ , we get: $a = w - 27$ . Substituting this into our first equation, we get the equation: $w = 4$ $(w - 27)$ which combines the information about $w$ from both of our original equations. Simplifying the right side of this equation, we get: $w = 4w - 108$ Solving for $w$ , we get: $3 w = 108$ $w = 36$.